The South African government reacted with anger to yesterday's bomb explosion in central Pretoria and threatened retaliatory raids on foreign "bases" of the opposition African National Congress.

Defense Minister Magnus Malan warned after the attack that South Africans would have to accustom themselves to living under wartime conditions. "We are involved in a low-profile revolutionary war which can be quickly transformed into a conventional war," he told reporters.

The death toll in the powerful bomb explosion outside the headquarters of the South African Air Force increased to 17 today, as one of the wounded died overnight. The blast injured 188 persons; many of the casualties were civilians.

The African National Congress, the main force fighting to end white-minority government, warned in a statement of more attacks against South Africa's armed forces but stopped short of claiming responsibility for the attack. The statement insisted that the bombing was directed against military establishments rather than civilians.

In the statement, telexed to The Associated Press in Johannesburg today from ANC headquarters in Lusaka, Zambia, the ANC declared:

"The escalating armed struggle, which was imposed on us as a result of the intransigence and violence of the apartheid regime, will make itself felt among an increasing number of those who have chosen to serve in the enemy's forces of repression."

In Nairobi, Kenya, AP quoted ANC head Oliver Tambo as saying, "Never again are our people going to be doing all of the bleeding. Don't you think we have offered the other cheek so many times so there is no cheek left to offer?"

Defense Minister Malan, calling the attack part of a communist "total onslaught," said last night he would not hesitate to order more preemptive raids on ANC "bases" in neighboring black countries, such as the commando attack last December killing 42 people in the Lesotho capital of Maseru.

"We mustn't sit around waiting for atrocities like this to happen," Malan said. "We've got to do something about it."

Many countries, including the United States, condemned South Africa in strong terms for the Maseru raid, which the South African government claimed was directed at African congress "terrorists" harbored there. The African congress and the Lesotho government said the victims were a mixture of refugees and local citizens.

Malan did not direct his threat at any particular country, but Mozambique is thought to be the one that South Africa most suspects of harboring congress activists.

Black political spokesmen in South Africa have joined whites in condemning the bomb attack, which caused many civilian casualties in the crowded street during the late afternoon rush hour.

All white opposition political parties--as well as the South African Council of Churches, which is headed by leading black spokesman Bishop Desmond Tutu--denounced the bomb attack as an atrocity. But there is an undercurrent of concern among the groups that the government may use it to justify intensified security police surveillance and to build up a war psychosis in the country.

Chief Gatsha Buthelezi, the most important black leader still committed to trying to end white minority rule by peaceful means, said he was "dismayed" by the attack, which he described as "terrible news."

Ntatho Motlana, chairman of the black township of Soweto's Committee of Ten and a spokesman for more radical blacks, said even those broadly sympathetic to the congress disapproved of this attack with its heavy civilian casualties.

In a telephone interview from Soweto, Motlana said many blacks he had spoken to there today expressed doubts about whether the congress could have been responsible because it has followed a policy of not attacking civilian targets.

"Some people think it may have been a breakaway group or someone trying to discredit the ANC," Motlana said.

"I want to express my own horror at this kind of thing. I think it unlikely that the ANC could have been responsible. It is not in line with what they have always led us to believe they would do, which was to attack only what they call military targets."

The ANC statement to the AP from Lusaka clearly expressed approval of the attack and said, "all available evidence clearly shows that the attack was directed at military establishments of the South African regime. Enemy casualties consisted essentially of Air Force and military intelligence personnel."

According to details of the casualties published in The Star of Johannesburg today, 70 of the 205 casualties were military personnel and the rest civilians, many of them blacks.

According to the commissioner of police, Gen. Michael Geldenhuys, eight of the 17 dead were blacks and two of the whites were women.

A classified U.S. intelligence report on the ANC, described in a Washington Post story last November, estimated that the organization has 1,000 to 2,000 militants outside South Africa and as many as 3,000 inside the country. The report noted that violent attacks by the ANC were increasing but that the attacks appeared to avoid white casualties.

The report indicated that there has been an influx of younger, more militant leaders, which may lead to "changes in the group's strategy".